In solid ink printing technology, the print media is pre-heated by a preheater system in order to improve adhesion of the ink to the print media during the printing process. Drum maintenance oil is also applied to the printer drum to provide better transfer of the ink to the print media. The preheat temperature of the print media and the type of drum maintenance oil are factors that can affect print quality. A higher preheat temperature and a lower viscosity of drum maintenance oil can result in better ink adhesion to the print media.
In duplex printing (printing on both sides of the same piece of print media, e.g., a sheet of paper), the print media has simplex and duplex sides. The simplex side of the print media is the side printed first. The duplex side of the print media is printed second. In duplex printing, the print media is routed back to the preheater after printing on the simplex side. The print media is then fed through the preheater and onto the printing drum oriented so that the duplex side is printed.
When the print media is fed back to the preheater after printing on the simplex side, the ink on the simplex side can smudge as a result of many factors. These factors include a high preheat temperature, low viscosity of drum maintenance oil and pressure on the print media from the heating plates in the preheater. The smudging leaves streaks of ink on the simplex side of the duplex printed print media.